package com.xiaocui.utils;
/**
 * @author vstarcui
 */
class TransformUtil {
	static boolean outOfChina(double lat, double lng) {
		if ((lng < 72.004) || (lng > 137.8347)) {
			return true;
		}
		return (lat < 0.8293) || (lat > 55.8271);
	}

	private static double transformLat(double x, double y) {
		double ret =
				-100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
		ret += (20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
		ret += (20.0 * Math.sin(y * Math.PI) + 40.0 * Math.sin(y / 3.0 * Math.PI)) * 2.0 / 3.0;
		ret += (160.0 * Math.sin(y / 12.0 * Math.PI) + 320 * Math.sin(y * Math.PI / 30.0)) * 2.0 / 3.0;
		return ret;
	}

	private static double transformLon(double x, double y) {
		double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
		ret += (20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
		ret += (20.0 * Math.sin(x * Math.PI) + 40.0 * Math.sin(x / 3.0 * Math.PI)) * 2.0 / 3.0;
		ret +=
				(150.0 * Math.sin(x / 12.0 * Math.PI) + 300.0 * Math.sin(x / 30.0 * Math.PI)) * 2.0 / 3.0;
		return ret;
	}
	/**
	 *
	 * @param lat 纬度
	 * @param lng 经度
	 * @return delta[0] 是纬度差，delta[1]是经度差
	 */
	static double[] delta(double lat, double lng){
		double[] delta = new double[2];
		double a = 6378245.0;
		double ee = 0.00669342162296594323;
		double dLat = transformLat(lng-105.0, lat-35.0);
		double dLng = transformLon(lng-105.0, lat-35.0);
		double radLat = lat / 180.0 * Math.PI;
		double magic = Math.sin(radLat);
		magic = 1 - ee*magic*magic;
		double sqrtMagic = Math.sqrt(magic);
		delta[0] = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * Math.PI);
		delta[1] = (dLng * 180.0) / (a / sqrtMagic * Math.cos(radLat) * Math.PI);
		return delta;
	}
}
